Publications by authors named "Myriam Heiman"

33 Publications

An amygdala circuit that suppresses social engagement.

Nature 2021 May 31;593(7857):114-118. Epub 2021 Mar 31.

Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA, USA.

Innate social behaviours, such as mating and fighting, are fundamental to animal reproduction and survival. However, social engagements can also put an individual at risk. Little is known about the neural mechanisms that enable appropriate risk assessment and the suppression of hazardous social interactions. Here we identify the posteromedial nucleus of the cortical amygdala (COApm) as a locus required for the suppression of male mating when a female mouse is unhealthy. Using anatomical tracing, functional imaging and circuit-level epistatic analyses, we show that suppression of mating with an unhealthy female is mediated by the COApm projections onto the glutamatergic population of the medial amygdalar nucleus (MEA). We further show that the role of the COApm-to-MEA connection in regulating male mating behaviour relies on the neuromodulator thyrotropin-releasing hormone (TRH). TRH is expressed in the COApm, whereas the TRH receptor (TRHR) is found in the postsynaptic MEA glutamatergic neurons. Manipulating neural activity of TRH-expressing neurons in the COApm modulated male mating behaviour. In the MEA, activation of the TRHR pathway by ligand infusion inhibited mating even towards healthy female mice, whereas genetic ablation of TRHR facilitated mating with unhealthy individuals. In summary, we reveal a neural pathway that relies on the neuromodulator TRH to modulate social interactions according to the health status of the reciprocating individual. Individuals must balance the cost of social interactions relative to the benefit, as deficits in the ability to select healthy mates may lead to the spread of disease.
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http://dx.doi.org/10.1038/s41586-021-03413-6DOI Listing
May 2021

Shape deformation analysis reveals the temporal dynamics of cell-type-specific homeostatic and pathogenic responses to mutant huntingtin.

Elife 2021 Feb 23;10. Epub 2021 Feb 23.

Sorbonne Université, Centre National de la Recherche Scientifique UMR 8256, INSERM ERL U1164, Paris, France.

Loss of cellular homeostasis has been implicated in the etiology of several neurodegenerative diseases (NDs). However, the molecular mechanisms that underlie this loss remain poorly understood on a systems level in each case. Here, using a novel computational approach to integrate dimensional RNA-seq and in vivo neuron survival data, we map the temporal dynamics of homeostatic and pathogenic responses in four striatal cell types of Huntington's disease (HD) model mice. This map shows that most pathogenic responses are mitigated and most homeostatic responses are decreased over time, suggesting that neuronal death in HD is primarily driven by the loss of homeostatic responses. Moreover, different cell types may lose similar homeostatic processes, for example, endosome biogenesis and mitochondrial quality control in -expressing neurons and astrocytes. HD relevance is validated by human stem cell, genome-wide association study, and post-mortem brain data. These findings provide a new paradigm and framework for therapeutic discovery in HD and other NDs.
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http://dx.doi.org/10.7554/eLife.64984DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7901871PMC
February 2021

Choroid plexus NKCC1 mediates cerebrospinal fluid clearance during mouse early postnatal development.

Nat Commun 2021 01 19;12(1):447. Epub 2021 Jan 19.

Department of Pathology, Boston Children's Hospital, Boston, MA, 02115, USA.

Cerebrospinal fluid (CSF) provides vital support for the brain. Abnormal CSF accumulation, such as hydrocephalus, can negatively affect perinatal neurodevelopment. The mechanisms regulating CSF clearance during the postnatal critical period are unclear. Here, we show that CSF K, accompanied by water, is cleared through the choroid plexus (ChP) during mouse early postnatal development. We report that, at this developmental stage, the ChP showed increased ATP production and increased expression of ATP-dependent K transporters, particularly the Na, K, Cl, and water cotransporter NKCC1. Overexpression of NKCC1 in the ChP resulted in increased CSF K clearance, increased cerebral compliance, and reduced circulating CSF in the brain without changes in intracranial pressure in mice. Moreover, ChP-specific NKCC1 overexpression in an obstructive hydrocephalus mouse model resulted in reduced ventriculomegaly. Collectively, our results implicate NKCC1 in regulating CSF K clearance through the ChP in the critical period during postnatal neurodevelopment in mice.
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http://dx.doi.org/10.1038/s41467-020-20666-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7815709PMC
January 2021

Cell Type-Specific Transcriptomics Reveals that Mutant Huntingtin Leads to Mitochondrial RNA Release and Neuronal Innate Immune Activation.

Neuron 2020 09 17;107(5):891-908.e8. Epub 2020 Jul 17.

Department of Brain and Cognitive Sciences, MIT, Cambridge, MA 02139, USA; Picower Institute for Learning and Memory, Cambridge, MA 02139, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA. Electronic address:

The mechanisms by which mutant huntingtin (mHTT) leads to neuronal cell death in Huntington's disease (HD) are not fully understood. To gain new molecular insights, we used single nuclear RNA sequencing (snRNA-seq) and translating ribosome affinity purification (TRAP) to conduct transcriptomic analyses of caudate/putamen (striatal) cell type-specific gene expression changes in human HD and mouse models of HD. In striatal spiny projection neurons, the most vulnerable cell type in HD, we observe a release of mitochondrial RNA (mtRNA) (a potent mitochondrial-derived innate immunogen) and a concomitant upregulation of innate immune signaling in spiny projection neurons. Further, we observe that the released mtRNAs can directly bind to the innate immune sensor protein kinase R (PKR). We highlight the importance of studying cell type-specific gene expression dysregulation in HD pathogenesis and reveal that the activation of innate immune signaling in the most vulnerable HD neurons provides a novel framework to understand the basis of mHTT toxicity and raises new therapeutic opportunities.
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http://dx.doi.org/10.1016/j.neuron.2020.06.021DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7486278PMC
September 2020

Selective Neuronal Vulnerability in Alzheimer's Disease: A Network-Based Analysis.

Neuron 2020 09 29;107(5):821-835.e12. Epub 2020 Jun 29.

Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, NY 10065, USA.

A major obstacle to treating Alzheimer's disease (AD) is our lack of understanding of the molecular mechanisms underlying selective neuronal vulnerability, a key characteristic of the disease. Here, we present a framework integrating high-quality neuron-type-specific molecular profiles across the lifetime of the healthy mouse, which we generated using bacTRAP, with postmortem human functional genomics and quantitative genetics data. We demonstrate human-mouse conservation of cellular taxonomy at the molecular level for neurons vulnerable and resistant in AD, identify specific genes and pathways associated with AD neuropathology, and pinpoint a specific functional gene module underlying selective vulnerability, enriched in processes associated with axonal remodeling, and affected by amyloid accumulation and aging. We have made all cell-type-specific profiles and functional networks available at http://alz.princeton.edu. Overall, our study provides a molecular framework for understanding the complex interplay between Aβ, aging, and neurodegeneration within the most vulnerable neurons in AD.
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http://dx.doi.org/10.1016/j.neuron.2020.06.010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7580783PMC
September 2020

Interleukin-6 deficiency exacerbates Huntington's disease model phenotypes.

Mol Neurodegener 2020 05 24;15(1):29. Epub 2020 May 24.

Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, 02139, USA.

Huntington's disease (HD) is an incurable neurodegenerative disorder caused by CAG trinucleotide expansions in the huntingtin gene. Markers of both systemic and CNS immune activation and inflammation have been widely noted in HD and mouse models of HD. In particular, elevation of the pro-inflammatory cytokine interleukin-6 (IL-6) is the earliest reported marker of immune activation in HD, and this elevation has been suggested to contribute to HD pathogenesis. To test the hypothesis that IL-6 deficiency would be protective against the effects of mutant huntingtin, we generated R6/2 HD model mice that lacked IL-6. Contrary to our prediction, IL-6 deficiency exacerbated HD-model associated behavioral phenotypes. Single nuclear RNA Sequencing (snRNA-seq) analysis of striatal cell types revealed that IL-6 deficiency led to the dysregulation of various genes associated with synaptic function, as well as the BDNF receptor Ntrk2. These data suggest that IL-6 deficiency exacerbates the effects of mutant huntingtin through dysregulation of genes of known relevance to HD pathobiology in striatal neurons, and further suggest that modulation of IL-6 to a level that promotes proper regulation of genes associated with synaptic function may hold promise as an HD therapeutic target.
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http://dx.doi.org/10.1186/s13024-020-00379-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7247164PMC
May 2020

Genome-wide In Vivo CNS Screening Identifies Genes that Modify CNS Neuronal Survival and mHTT Toxicity.

Neuron 2020 04 30;106(1):76-89.e8. Epub 2020 Jan 30.

Department of Brain and Cognitive Sciences, MIT, Cambridge, MA 02139, USA; Picower Institute for Learning and Memory, Cambridge, MA 02139, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA. Electronic address:

Unbiased in vivo genome-wide genetic screening is a powerful approach to elucidate new molecular mechanisms, but such screening has not been possible to perform in the mammalian central nervous system (CNS). Here, we report the results of the first genome-wide genetic screens in the CNS using both short hairpin RNA (shRNA) and CRISPR libraries. Our screens identify many classes of CNS neuronal essential genes and demonstrate that CNS neurons are particularly sensitive not only to perturbations to synaptic processes but also autophagy, proteostasis, mRNA processing, and mitochondrial function. These results reveal a molecular logic for the common implication of these pathways across multiple neurodegenerative diseases. To further identify disease-relevant genetic modifiers, we applied our screening approach to two mouse models of Huntington's disease (HD). Top mutant huntingtin toxicity modifier genes included several Nme genes and several genes involved in methylation-dependent chromatin silencing and dopamine signaling, results that reveal new HD therapeutic target pathways.
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http://dx.doi.org/10.1016/j.neuron.2020.01.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7181458PMC
April 2020

A cortical-brainstem circuit predicts and governs compulsive alcohol drinking.

Science 2019 11;366(6468):1008-1012

The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.

What individual differences in neural activity predict the future escalation of alcohol drinking from casual to compulsive? The neurobiological mechanisms that gate the transition from moderate to compulsive drinking remain poorly understood. We longitudinally tracked the development of compulsive drinking across a binge-drinking experience in male mice. Binge drinking unmasked individual differences, revealing latent traits in alcohol consumption and compulsive drinking despite equal prior exposure to alcohol. Distinct neural activity signatures of cortical neurons projecting to the brainstem before binge drinking predicted the ultimate emergence of compulsivity. Mimicry of activity patterns that predicted drinking phenotypes was sufficient to bidirectionally modulate drinking. Our results provide a mechanistic explanation for individual variance in vulnerability to compulsive alcohol drinking.
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http://dx.doi.org/10.1126/science.aay1186DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6989100PMC
November 2019

Small Molecule Targets TMED9 and Promotes Lysosomal Degradation to Reverse Proteinopathy.

Cell 2019 07;178(3):521-535.e23

Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA.

Intracellular accumulation of misfolded proteins causes toxic proteinopathies, diseases without targeted therapies. Mucin 1 kidney disease (MKD) results from a frameshift mutation in the MUC1 gene (MUC1-fs). Here, we show that MKD is a toxic proteinopathy. Intracellular MUC1-fs accumulation activated the ATF6 unfolded protein response (UPR) branch. We identified BRD4780, a small molecule that clears MUC1-fs from patient cells, from kidneys of knockin mice and from patient kidney organoids. MUC1-fs is trapped in TMED9 cargo receptor-containing vesicles of the early secretory pathway. BRD4780 binds TMED9, releases MUC1-fs, and re-routes it for lysosomal degradation, an effect phenocopied by TMED9 deletion. Our findings reveal BRD4780 as a promising lead for the treatment of MKD and other toxic proteinopathies. Generally, we elucidate a novel mechanism for the entrapment of misfolded proteins by cargo receptors and a strategy for their release and anterograde trafficking to the lysosome.
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http://dx.doi.org/10.1016/j.cell.2019.07.002DOI Listing
July 2019

"For Paul".

Nat Neurosci 2019 08;22(8):1203-1204

Nash Family Department of Neuroscience, Department of Psychiatry, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.

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http://dx.doi.org/10.1038/s41593-019-0450-zDOI Listing
August 2019

Widespread Accumulation of Ribosome-Associated Isolated 3' UTRs in Neuronal Cell Populations of the Aging Brain.

Cell Rep 2018 11;25(9):2447-2456.e4

Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139, USA. Electronic address:

Particular brain regions and cell populations exhibit increased susceptibility to aging-related stresses. Here, we describe the age-specific and brain-region-specific accumulation of ribosome-associated 3' UTR RNAs that lack the 5' UTR and open reading frame. Our study reveals that this phenomenon impacts hundreds of genes in aged D1 spiny projection neurons of the mouse striatum and also occurs in the aging human brain. Isolated 3' UTR accumulation is tightly correlated with mitochondrial gene expression and oxidative stress, with full-length mRNA expression that is reduced but not eliminated, and with production of short 3' UTR-encoded peptides. Depletion of the oxidation-sensitive Fe-S cluster ribosome recycling factor ABCE1 induces the accumulation of 3' UTRs, consistent with a model in which ribosome stalling and mRNA cleavage by No-Go decay yields isolated 3' UTR RNAs protected by ribosomes. Isolated 3' UTR accumulation is a hallmark of brain aging, likely reflecting regional differences in metabolism and oxidative stress.
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http://dx.doi.org/10.1016/j.celrep.2018.10.094DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6354779PMC
November 2018

Normal aging induces A1-like astrocyte reactivity.

Proc Natl Acad Sci U S A 2018 02 7;115(8):E1896-E1905. Epub 2018 Feb 7.

Department of Neurobiology, Stanford University, School of Medicine, Stanford, CA 94305.

The decline of cognitive function occurs with aging, but the mechanisms responsible are unknown. Astrocytes instruct the formation, maturation, and elimination of synapses, and impairment of these functions has been implicated in many diseases. These findings raise the question of whether astrocyte dysfunction could contribute to cognitive decline in aging. We used the Bac-Trap method to perform RNA sequencing of astrocytes from different brain regions across the lifespan of the mouse. We found that astrocytes have region-specific transcriptional identities that change with age in a region-dependent manner. We validated our findings using fluorescence in situ hybridization and quantitative PCR. Detailed analysis of the differentially expressed genes in aging revealed that aged astrocytes take on a reactive phenotype of neuroinflammatory A1-like reactive astrocytes. Hippocampal and striatal astrocytes up-regulated a greater number of reactive astrocyte genes compared with cortical astrocytes. Moreover, aged brains formed many more A1 reactive astrocytes in response to the neuroinflammation inducer lipopolysaccharide. We found that the aging-induced up-regulation of reactive astrocyte genes was significantly reduced in mice lacking the microglial-secreted cytokines (IL-1α, TNF, and C1q) known to induce A1 reactive astrocyte formation, indicating that microglia promote astrocyte activation in aging. Since A1 reactive astrocytes lose the ability to carry out their normal functions, produce complement components, and release a toxic factor which kills neurons and oligodendrocytes, the aging-induced up-regulation of reactive genes by astrocytes could contribute to the cognitive decline in vulnerable brain regions in normal aging and contribute to the greater vulnerability of the aged brain to injury.
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http://dx.doi.org/10.1073/pnas.1800165115DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5828643PMC
February 2018

Control of Huntington's Disease-Associated Phenotypes by the Striatum-Enriched Transcription Factor Foxp2.

Cell Rep 2017 Dec;21(10):2688-2695

Department of Brain and Cognitive Sciences, MIT, Cambridge, MA 02139, USA; Picower Institute for Learning and Memory, Cambridge, MA 02139, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA. Electronic address:

Alteration of corticostriatal glutamatergic function is an early pathophysiological change associated with Huntington's disease (HD). The factors that regulate the maintenance of corticostriatal glutamatergic synapses post-developmentally are not well understood. Recently, the striatum-enriched transcription factor Foxp2 was implicated in the development of these synapses. Here, we show that, in mice, overexpression of Foxp2 in the adult striatum of two models of HD leads to rescue of HD-associated behaviors, while knockdown of Foxp2 in wild-type mice leads to development of HD-associated behaviors. We note that Foxp2 encodes the longest polyglutamine repeat protein in the human reference genome, and we show that it can be sequestered into aggregates with polyglutamine-expanded mutant Huntingtin protein (mHTT). Foxp2 overexpression in HD model mice leads to altered expression of several genes associated with synaptic function, genes that present additional targets for normalization of corticostriatal dysfunction in HD.
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http://dx.doi.org/10.1016/j.celrep.2017.11.018DOI Listing
December 2017

Identifying therapeutic targets by combining transcriptional data with ordinal clinical measurements.

Nat Commun 2017 09 20;8(1):623. Epub 2017 Sep 20.

Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts, 02139, USA.

The immense and growing repositories of transcriptional data may contain critical insights for developing new therapies. Current approaches to mining these data largely rely on binary classifications of disease vs. control, and are not able to incorporate measures of disease severity. We report an analytical approach to integrate ordinal clinical information with transcriptomics. We apply this method to public data for a large cohort of Huntington's disease patients and controls, identifying and prioritizing phenotype-associated genes. We verify the role of a high-ranked gene in dysregulation of sphingolipid metabolism in the disease and demonstrate that inhibiting the enzyme, sphingosine-1-phosphate lyase 1 (SPL), has neuroprotective effects in Huntington's disease models. Finally, we show that one consequence of inhibiting SPL is intracellular inhibition of histone deacetylases, thus linking our observations in sphingolipid metabolism to a well-characterized Huntington's disease pathway. Our approach is easily applied to any data with ordinal clinical measurements, and may deepen our understanding of disease processes.Identifying gene subsets affecting disease phenotypes from transcriptome data is challenge. Here, the authors develop a method that combines transcriptional data with disease ordinal clinical measurements to discover a sphingolipid metabolism regulator involving in Huntington's disease progression.
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http://dx.doi.org/10.1038/s41467-017-00353-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5606996PMC
September 2017

Resolving CNS mRNA Heterogeneity: Examining mRNA Alternative Polyadenylation at a Cell-Type-Specific Level.

Neuron 2017 Sep;95(6):1232-1233

Broad Institute of MIT and Harvard, 415 Main Street, Cambridge, MA 02142, USA; MIT Department of Brain and Cognitive Sciences, 43 Vassar Street, Cambridge, MA 02139, USA; Picower Institute for Learning and Memory, 43 Vassar Street, Cambridge, MA 02139, USA. Electronic address:

Alternative polyadenylation often regulates mRNA isoform usage. In this issue of Neuron, Hwang et al. (2017) describe a powerful new cell-type-specific methodology, cTag-PAPERCLIP, which can be used to study alternative polyadenylation in the CNS.
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http://dx.doi.org/10.1016/j.neuron.2017.08.045DOI Listing
September 2017

Hypothalamic Amylin Acts in Concert with Leptin to Regulate Food Intake.

Cell Metab 2015 Dec 19;22(6):1059-67. Epub 2015 Nov 19.

Laboratory of Molecular Genetics, The Rockefeller University, New York, NY 10065, USA; Howard Hughes Medical Institute, 4000 Jones Bridge Road, Chevy Chase, MD 20815-6789, USA. Electronic address:

In this report we evaluated the functions of hypothalamic amylin in vivo and in vitro. Profiling of hypothalamic neurons revealed that islet amyloid polypeptide (Iapp, precursor to amylin) is expressed in neurons in the lateral hypothalamus, arcuate nucleus, medial preoptic area, and elsewhere. Hypothalamic expression of lapp is markedly decreased in ob/ob mice and normalized by exogenous leptin. In slices, amylin and leptin had similar electrophysiologic effects on lateral hypothalamic leptin receptor ObRb-expressing neurons, while the amylin antagonist AC187 inhibited their activity and blunted the effect of leptin. Finally, i.c.v. infusion of AC187 acutely reduced the anorectic effects of leptin. These data show that hypothalamic amylin is transcriptionally regulated by leptin, that it can act directly on ObRb neurons in concert with leptin, and that it regulates feeding. These findings provide a potential mechanism for the increased efficacy of a metreleptin/pramlintide combination therapy for obesity.
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http://dx.doi.org/10.1016/j.cmet.2015.10.012DOI Listing
December 2015

The Stress-Induced Atf3-Gelsolin Cascade Underlies Dendritic Spine Deficits in Neuronal Models of Tuberous Sclerosis Complex.

J Neurosci 2015 Jul;35(30):10762-72

F.M. Kirby Neurobiology Center, Department of Neurology, Children's Hospital Boston, Harvard Medical School, Boston, Massachusetts 02115,

Unlabelled: Hyperactivation of the mechanistic target of rapamycin (mTOR) kinase, as a result of loss-of-function mutations in tuberous sclerosis complex 1 (TSC1) or TSC2 genes, causes protein synthesis dysregulation, increased cell size, and aberrant neuronal connectivity. Dysregulated synthesis of synaptic proteins has been implicated in the pathophysiology of autism spectrum disorder (ASD) associated with TSC and fragile X syndrome. However, cell type-specific translational profiles in these disease models remain to be investigated. Here, we used high-fidelity and unbiased Translating Ribosome Affinity Purification (TRAP) methodology to purify ribosome-associated mRNAs and identified translational alterations in a rat neuronal culture model of TSC. We find that expression of many stress and/or activity-dependent proteins is highly induced while some synaptic proteins are repressed. Importantly, transcripts for the activating transcription factor-3 (Atf3) and mitochondrial uncoupling protein-2 (Ucp2) are highly induced in Tsc2-deficient neurons, as well as in a neuron-specific Tsc1 conditional knock-out mouse model, and show differential responses to the mTOR inhibitor rapamycin. Gelsolin, a known target of Atf3 transcriptional activity, is also upregulated. shRNA-mediated block of Atf3 induction suppresses expression of gelsolin, an actin-severing protein, and rescues spine deficits found in Tsc2-deficient neurons. Together, our data demonstrate that a cell-autonomous program consisting of a stress-induced Atf3-gelsolin cascade affects the change in dendritic spine morphology following mTOR hyperactivation. This previously unidentified molecular cascade could be a therapeutic target for treating mTORopathies.

Significance Statement: Tuberous sclerosis complex (TSC) is a genetic disease associated with epilepsy and autism. Dysregulated protein synthesis has been implicated as a cause of this disease. However, cell type-specific translational profiles that are aberrant in this disease are unknown. Here we show that expression of many stress and/or activity-dependent proteins is highly induced while some synaptic proteins are repressed in neurons missing the Tsc2 gene expression. Identification of genes whose translation is abnormal in TSC may provide insights to previously unidentified therapeutic targets.
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http://dx.doi.org/10.1523/JNEUROSCI.4796-14.2015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4518051PMC
July 2015

Protein kinase A directly phosphorylates metabotropic glutamate receptor 5 to modulate its function.

J Neurochem 2015 Mar 4;132(6):677-86. Epub 2015 Mar 4.

Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, New York, USA; Department of Pharmacology, Kurume University School of Medicine, Kurume, Fukuoka, Japan; Department of Psychiatry, Kurume University School of Medicine, Kurume, Fukuoka, Japan; Cognitive and Molecular Research Institute of Brain Diseases, Kurume University, Kurume, Fukuoka, Japan.

Metabotropic glutamate receptor 5 (mGluR5) regulates excitatory post-synaptic signaling in the central nervous system (CNS) and is implicated in various CNS disorders. Protein kinase A (PKA) signaling is known to play a critical role in neuropsychiatric disorders such as Parkinson's disease, schizophrenia, and addiction. Dopamine signaling is known to modulate the properties of mGluR5 in a cAMP- and PKA-dependent manner, suggesting that mGluR5 may be a direct target for PKA. Our study identifies mGluR5 at Ser870 as a direct substrate for PKA phosphorylation and demonstrates that this phosphorylation plays a critical role in the PKA-mediated modulation of mGluR5 functions such as extracellular signal-regulated kinase phosphorylation and intracellular Ca(2+) oscillations. The identification of the molecular mechanism by which PKA signaling modulates mGluR5-mediated cellular responses contributes to the understanding of the interaction between dopaminergic and glutamatergic neuronal signaling. We identified serine residue 870 (S870) in metabotropic glutamate receptor 5 (mGluR5) as a direct substrate for protein kinase A (PKA). The phosphorylation of this site regulates the ability of mGluR5 to induce extracellular signal-regulated kinase (ERK) phosphorylation and intracellular Ca(2+) oscillations. This study provides a direct molecular mechanism by which PKA signaling interacts with glutamate neurotransmission.
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http://dx.doi.org/10.1111/jnc.13038DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4359654PMC
March 2015

Synthetic lethal screening in the mammalian central nervous system identifies Gpx6 as a modulator of Huntington's disease.

Proc Natl Acad Sci U S A 2015 Jan 22;112(1):268-72. Epub 2014 Dec 22.

The Broad Institute of MIT and Harvard University, Cambridge, MA 02142; The Picower Institute for Learning and Memory, Cambridge, MA 02139; and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139

Huntington's disease, the most common inherited neurodegenerative disease, is characterized by a dramatic loss of deep-layer cortical and striatal neurons, as well as morbidity in midlife. Human genetic studies led to the identification of the causative gene, huntingtin. Recent genomic advances have also led to the identification of hundreds of potential interacting partners for huntingtin protein and many hypotheses as to the molecular mechanisms whereby mutant huntingtin leads to cellular dysfunction and death. However, the multitude of possible interacting partners and cellular pathways affected by mutant huntingtin has complicated efforts to understand the etiology of this disease, and to date no curative therapeutic exists. To address the general problem of identifying the disease-phenotype contributing genes from a large number of correlative studies, here we develop a synthetic lethal screening methodology for the mammalian central nervous system, called SLIC, for synthetic lethal in the central nervous system. Applying SLIC to the study of Huntington's disease, we identify the age-regulated glutathione peroxidase 6 (Gpx6) gene as a modulator of mutant huntingtin toxicity and show that overexpression of Gpx6 can dramatically alleviate both behavioral and molecular phenotypes associated with a mouse model of Huntington's disease. SLIC can, in principle, be used in the study of any neurodegenerative disease for which a mouse model exists, promising to reveal modulators of neurodegenerative disease in an unbiased fashion, akin to screens in simpler model organisms.
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http://dx.doi.org/10.1073/pnas.1417231112DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4291668PMC
January 2015

Nitric oxide regulates synaptic transmission between spiny projection neurons.

Proc Natl Acad Sci U S A 2014 Dec 20;111(49):17636-41. Epub 2014 Nov 20.

Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, NY 10065;

Recurrent axon collaterals are a major means of communication between spiny projection neurons (SPNs) in the striatum and profoundly affect the function of the basal ganglia. However, little is known about the molecular and cellular mechanisms that underlie this communication. We show that intrastriatal nitric oxide (NO) signaling elevates the expression of the vesicular GABA transporter (VGAT) within recurrent collaterals of SPNs. Down-regulation of striatal NO signaling resulted in an attenuation of GABAergic signaling in SPN local collaterals, down-regulation of VGAT expression in local processes of SPNs, and impaired motor behavior. PKG1 and cAMP response element-binding protein are involved in the signal transduction that transcriptionally regulates VGAT by NO. These data suggest that transcriptional control of the vesicular GABA transporter by NO regulates GABA transmission and action selection.
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http://dx.doi.org/10.1073/pnas.1420162111DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4267338PMC
December 2014

Cell type-specific plasticity of striatal projection neurons in parkinsonism and L-DOPA-induced dyskinesia.

Nat Commun 2014 Oct 31;5:5316. Epub 2014 Oct 31.

Department of Physiology, Feinberg School of Medicine, Northwestern University, 303 East Chicago Avenue, Chicago, Illinois 60611, USA.

The striatum is widely viewed as the fulcrum of pathophysiology in Parkinson's disease (PD) and L-DOPA-induced dyskinesia (LID). In these disease states, the balance in activity of striatal direct pathway spiny projection neurons (dSPNs) and indirect pathway spiny projection neurons (iSPNs) is disrupted, leading to aberrant action selection. However, it is unclear whether countervailing mechanisms are engaged in these states. Here we report that iSPN intrinsic excitability and excitatory corticostriatal synaptic connectivity were lower in PD models than normal; L-DOPA treatment restored these properties. Conversely, dSPN intrinsic excitability was elevated in tissue from PD models and suppressed in LID models. Although the synaptic connectivity of dSPNs did not change in PD models, it fell with L-DOPA treatment. In neither case, however, was the strength of corticostriatal connections globally scaled. Thus, SPNs manifested homeostatic adaptations in intrinsic excitability and in the number but not strength of excitatory corticostriatal synapses.
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http://dx.doi.org/10.1038/ncomms6316DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4431763PMC
October 2014

Cell type-specific mRNA purification by translating ribosome affinity purification (TRAP).

Nat Protoc 2014 8;9(6):1282-91. Epub 2014 May 8.

Laboratory of Molecular Biology, Howard Hughes Medical Institute, The Rockefeller University, New York, New York, USA.

Cellular diversity and architectural complexity create barriers to understanding the function of the mammalian CNS at a molecular level. To address this problem, we have recently developed a methodology that provides the ability to profile the entire translated mRNA complement of any genetically defined cell population. This methodology, which we termed translating ribosome affinity purification, or TRAP, combines cell type-specific transgene expression with affinity purification of translating ribosomes. TRAP can be used to study the cell type-specific mRNA profiles of any genetically defined cell type, and it has been used in organisms ranging from Drosophila melanogaster to mice and human cultured cells. Unlike other methodologies that rely on microdissection, cell panning or cell sorting, the TRAP methodology bypasses the need for tissue fixation or single-cell suspensions (and the potential artifacts that these treatments introduce) and reports on mRNAs in the entire cell body. This protocol provides a step-by-step guide to implement the TRAP methodology, which takes 2 d to complete once all materials are in hand.
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http://dx.doi.org/10.1038/nprot.2014.085DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4102313PMC
December 2014

Molecular adaptations of striatal spiny projection neurons during levodopa-induced dyskinesia.

Proc Natl Acad Sci U S A 2014 Mar 5;111(12):4578-83. Epub 2014 Mar 5.

Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, NY 10065.

Levodopa treatment is the major pharmacotherapy for Parkinson's disease. However, almost all patients receiving levodopa eventually develop debilitating involuntary movements (dyskinesia). Although it is known that striatal spiny projection neurons (SPNs) are involved in the genesis of this movement disorder, the molecular basis of dyskinesia is not understood. In this study, we identify distinct cell-type-specific gene-expression changes that occur in subclasses of SPNs upon induction of a parkinsonian lesion followed by chronic levodopa treatment. We identify several hundred genes, the expression of which is correlated with levodopa dose, many of which are under the control of activator protein-1 and ERK signaling. Despite homeostatic adaptations involving several signaling modulators, activator protein-1-dependent gene expression remains highly dysregulated in direct pathway SPNs upon chronic levodopa treatment. We also discuss which molecular pathways are most likely to dampen abnormal dopaminoceptive signaling in spiny projection neurons, hence providing potential targets for antidyskinetic treatments in Parkinson's disease.
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http://dx.doi.org/10.1073/pnas.1401819111DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3970487PMC
March 2014

Differential effects of cocaine on histone posttranslational modifications in identified populations of striatal neurons.

Proc Natl Acad Sci U S A 2013 Jun 20;110(23):9511-6. Epub 2013 May 20.

Unité Mixte de Recherche en Santé 839, Institut National de la Santé et de la Recherche Médicale, 75005 Paris, France.

Drugs of abuse, such as cocaine, induce changes in gene expression and epigenetic marks including alterations in histone posttranslational modifications in striatal neurons. These changes are thought to participate in physiological memory mechanisms and to be critical for long-term behavioral alterations. However, the striatum is composed of multiple cell types, including two distinct populations of medium-sized spiny neurons, and little is known concerning the cell-type specificity of epigenetic modifications. To address this question we used bacterial artificial chromosome transgenic mice, which express EGFP fused to the N-terminus of the large subunit ribosomal protein L10a driven by the D1 or D2 dopamine receptor (D1R, D2R) promoter, respectively. Fluorescence in nucleoli was used to sort nuclei from D1R- or D2R-expressing neurons and to quantify by flow cytometry the cocaine-induced changes in histone acetylation and methylation specifically in these two types of nuclei. The two populations of medium-sized spiny neurons displayed different patterns of histone modifications 15 min or 24 h after a single injection of cocaine or 24 h after seven daily injections. In particular, acetylation of histone 3 on Lys 14 and of histone 4 on Lys 5 and 12, and methylation of histone 3 on Lys 9 exhibited distinct and persistent changes in the two cell types. Our data provide insights into the differential epigenetic responses to cocaine in D1R- and D2R-positive neurons and their potential regulation, which may participate in the persistent effects of cocaine in these neurons. The method described should have general utility for studying nuclear modifications in different types of neuronal or nonneuronal cell types.
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http://dx.doi.org/10.1073/pnas.1307116110DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3677456PMC
June 2013

IRE1α induces thioredoxin-interacting protein to activate the NLRP3 inflammasome and promote programmed cell death under irremediable ER stress.

Cell Metab 2012 Aug;16(2):250-64

Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA.

When unfolded proteins accumulate to irremediably high levels within the endoplasmic reticulum (ER), intracellular signaling pathways called the unfolded protein response (UPR) become hyperactivated to cause programmed cell death. We discovered that thioredoxin-interacting protein (TXNIP) is a critical node in this "terminal UPR." TXNIP becomes rapidly induced by IRE1α, an ER bifunctional kinase/endoribonuclease (RNase). Hyperactivated IRE1α increases TXNIP mRNA stability by reducing levels of a TXNIP destabilizing microRNA, miR-17. In turn, elevated TXNIP protein activates the NLRP3 inflammasome, causing procaspase-1 cleavage and interleukin 1β (IL-1β) secretion. Txnip gene deletion reduces pancreatic β cell death during ER stress and suppresses diabetes caused by proinsulin misfolding in the Akita mouse. Finally, small molecule IRE1α RNase inhibitors suppress TXNIP production to block IL-1β secretion. In summary, the IRE1α-TXNIP pathway is used in the terminal UPR to promote sterile inflammation and programmed cell death and may be targeted to develop effective treatments for cell degenerative diseases.
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http://dx.doi.org/10.1016/j.cmet.2012.07.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4014071PMC
August 2012

Strain-specific regulation of striatal phenotype in Drd2-eGFP BAC transgenic mice.

J Neurosci 2012 Jul;32(27):9124-32

Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA.

Mice carrying bacterial artificial chromosome (BAC) transgenes have become important tools for neuroscientists, providing a powerful means of dissecting complex neural circuits in the brain. Recently, it was reported that one popular line of these mice--mice possessing a BAC transgene with a D(2) dopamine receptor (Drd2) promoter construct coupled to an enhanced green fluorescent protein (eGFP) reporter--had abnormal striatal gene expression, physiology, and motor behavior. Unlike most of the work using BAC mice, this interesting study relied upon mice backcrossed on the outbred Swiss Webster (SW) strain that were homozygous for the Drd2-eGFP BAC transgene. The experiments reported here were conducted to determine whether mouse strain or zygosity was a factor in the reported abnormalities. As reported, SW mice were very sensitive to transgene expression. However, in more commonly used inbred strains of mice (C57BL/6, FVB/N) that were hemizygous for the transgene, the Drd2-eGFP BAC transgene did not alter striatal gene expression, physiology, or motor behavior. Thus, the use of inbred strains of mice that are hemizygous for the Drd2 BAC transgene provides a reliable tool for studying basal ganglia function.
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http://dx.doi.org/10.1523/JNEUROSCI.0229-12.2012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3461272PMC
July 2012

Inhibition of mTOR signaling in Parkinson's disease prevents L-DOPA-induced dyskinesia.

Sci Signal 2009 Jul 21;2(80):ra36. Epub 2009 Jul 21.

Department of Neuroscience, Karolinska Institutet, Retzius väg 8, 171 77 Stockholm, Sweden.

Parkinson's disease (PD), a disorder caused by degeneration of the dopaminergic input to the basal ganglia, is commonly treated with l-DOPA. Use of this drug, however, is severely limited by motor side effects, or dyskinesia. We show that administration of l-DOPA in a mouse model of Parkinsonism led to dopamine D1 receptor-mediated activation of the mammalian target of rapamycin (mTOR) complex 1 (mTORC1), which is implicated in several forms of synaptic plasticity. This response occurred selectively in the GABAergic medium spiny neurons that project directly from the striatum to the output structures of the basal ganglia. The l-DOPA-mediated activation of mTORC1 persisted in mice that developed dyskinesia. Moreover, the mTORC1 inhibitor rapamycin prevented the development of dyskinesia without affecting the therapeutic efficacy of l-DOPA. Thus, the mTORC1 signaling cascade represents a promising target for the design of anti-Parkinsonian therapies.
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http://dx.doi.org/10.1126/scisignal.2000308DOI Listing
July 2009

L-DOPA activates ERK signaling and phosphorylates histone H3 in the striatonigral medium spiny neurons of hemiparkinsonian mice.

J Neurochem 2009 Feb;108(3):621-33

Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.

In the dopamine-depleted striatum, extracellular signal-regulated kinase (ERK) signaling is implicated in the development of L-DOPA-induced dyskinesia. To gain insights on its role in this disorder, we examined the effects of L-DOPA on the state of phosphorylation of ERK and downstream target proteins in striatopallidal and striatonigral medium spiny neurons (MSNs). For this purpose, we employed mice expressing enhanced green fluorescent protein (EGFP) under the control of the promoters for the dopamine D(2) receptor (Drd2-EGFP mice) or the dopamine D(1) receptor (Drd1a-EGFP mice), which are expressed in striatopallidal and striatonigral MSNs, respectively. In 6-hydroxydopamine-lesioned Drd2-EGFP mice, L-DOPA increased the phosphorylation of ERK, mitogen- and stress-activated kinase 1 and histone H3, selectively in EGFP-negative MSNs. Conversely, a complete co-localization between EGFP and these phosphoproteins was observed in Drd1a-EGFP mice. The effect of L-DOPA was prevented by blockade of dopamine D(1) receptors. The same pattern of activation of ERK signaling was observed in dyskinetic mice, after repeated administration of L-DOPA. Our results demonstrate that in the dopamine-depleted striatum, L-DOPA activates ERK signaling specifically in striatonigral MSNs. This regulation may result in ERK-dependent changes in striatal plasticity leading to dyskinesia.
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http://dx.doi.org/10.1111/j.1471-4159.2008.05831.xDOI Listing
February 2009